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Javascript(leetcode#34) Find First and Last Position of Element in Sorted Array

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Difficult:Medium

題目

Given an array of integers nums sorted in non-decreasing order, find the starting and ending position of a given target value.

If target is not found in the array, return [-1, -1].

You must write an algorithm with O(log n) runtime complexity.

翻譯

給定一個按非降序排序的整數數組 nums，找到給定目標值的開始和結束位置。

如果在數組中找不到目標，則返回 [-1, -1]。

您必須編寫一個具有 O(log n) 運行時復雜度的算法。

範例

Example 1:

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Input: nums = [5,7,7,8,8,10], target = 8
Output: [3,4]

Example 2:

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Input: nums = [5,7,7,8,8,10], target = 6
Output: [-1,-1]

Example 3:

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Input: nums = [], target = 0
Output: [-1,-1]

解題思路

Solution

Code 1 :

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var searchRange = function (nums, target) {
    let index = nums.indexOf(target);
    if (index == -1) {
        return [-1, -1];
    } else {
        let end = index + 1;
        while (true) {
            if (nums[end] != target) {
                break;
            }
            end++;
        }
        return [index, end - 1]
    }
};